Continuing improvements in semiconductor processing technology for high frequency signal processing applications has made it possible to achieve a considerable reduction in the size of microminiaturized communication circuit components. This is particularly true where the signal processing components are physically packaged using surface-mount technologies, permitting a plurality of modules to be compactly nested in closed proximity of one another on a support board. However, a communication system consists of more than just an arrangement of signal processing devices; it also contains signal transmission links through which the devices are interconnected. As bandwidths for such components have increased well into the double digit GigaHertz range, the physical occupation area of the signal processing devices is often smaller than that of the transmission line interconnects. Moreover, since the support board, upon which the circuit device packages are surface-mounted, is typically made of a relatively lossy material (e.g. G-10 dielectric), the transmission line interconnect structure may suffer substantial attenuation, in addition to the large surface occupation area penalty it places on the packaging scheme.
To reduce the attenuation problem, the signal coupling lines may be mounted on a separate low-loss dielectric, such as a sheet of Teflon. Although the use of such a separate, low loss transmission line support structure may help reduce interconnect loss, it necessarily will increase the size of the overall packaging scheme. Unfortunately, in either approach, isolation between adjacent segments of interconnect remains relatively poor.